[diesel_john]

I run pure Seirra antifreeze in a cast iron block with aluminum heads. i did it to help prevent detonation. I boiled the water out of the mixture by turning off the fans and taking off the rad cap and letting ti idle until it got to 250 f and there were no more bubbles coming out. It doesn't even boil at 250 now with the cap off. no steam separation in the heads equals a better resistant to detontion. the solution is a little bit more viscous than 50/50 make sure you have a good enough water pump on cold starts to circulate in the block and the stock thermostat will run hotter because of this. i always take out the thermostat and drill a 1/16th hole thur it if its doesn't have a little air bypass check valve built in.